The younger brother of slain standover figure Walid Ahmad has been denied bail after being charged over a gangland shooting that sparked a series of revenge attacks that continue to rock Sydney.

Mahmoud "Brownie" Ahmad was nabbed by NSW Police at Sydney's international airport last night after arriving on a flight from the Middle East.

He was charged in relation to the murder of Safwan Charbaji, 32, who was fatally wounded outside a Condell Park smash repair business last April.

The 34-year-old had travelled to Lebanon soon after the bloody clash outside the A-Team Bodyworks shop, which claimed the life of Charbaji, and inflamed tensions between warring factions of Sydney's underworld that have simmered ever since.

Charbaji was shot in the head and chest through the windscreen of a car, which was then used to drive him to hospital.

A warrant remains outstanding for Fawaz Mohammed Elmir, 48, who has not been seen since the daylight gunfight outside the repair shop.

The violence reportedly erupted as a result of an argument over a $100,000 debt.

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It was well-known that the business was linked to notorious underworld figure Walid Ahmad, 40, and weeks later he was killed in a spray of bullets at the rooftop car park of Bankstown Central shopping centre.

The pattern of revenge executions continued in October, when 29-year-old hitman Hamad Assaad was gunned down by at least two men in the targeted attack outside his Georges Hall home.

A 34-year-old man was arrested at Sydney airport over a shooting in Sydney last year. (Supplied/NSW Police) ()

His killers apparently lay in wait, opening fire as Assaad stepped outside, before speeding off in a black sedan.

In a possible reprisal attack earlier this month, 29-year-old Kemal Barakat was killed in his Mortlake apartment on March 10.

Barakat, who was shot multiple times at close range in front of a woman who was at the home at the time, was linked to the death of Assaad.

Assaad had previously been linked to a 2015 bungled shooting in Leichhardt of Mafioso kingpin Pasquale Barbaro, who was executed a year later outside an Earlwood home in Sydney's southwest.